Clinical applications of indocyanine green (ICG) enhanced fluorescence in laparoscopic surgery

Usefulness of Fluorescence Vascular Imaging for Preserving the Remnant Stomach After Distal Pancreatosplenectomy: A Case Report

Due to recent developments in medical treatment, the number of patients that undergo multiple surgical procedures for secondary metachronous cancer is increasing. In cases in which patients undergo distal pancreatosplenectomy after distal gastrectomy, surgeons might have concerns about whether they are able to preserve the remnant proximal stomach because the main feeding vessels will have been divided in the previous procedure. Herein, we report a case in which a patient underwent distal pancreatosplenectomy 20 years after undergoing distal gastrectomy, and the remnant proximal stomach was successfully preserved with the help of intraoperative fluorescence vascular imaging using indocyanine green (FVI-ICG). A 65-year-old female was referred to our hospital due to upper gastric pain and was diagnosed with cancer of the pancreatic body. She had undergone distal gastrectomy 20 years earlier for early stage gastric cancer. Therefore, the blood supply to the remnant stomach left after the distal pancreatectomy procedure might have been insufficient. To determine the adequacy of the blood supply to the remnant proximal stomach after distal pancreatosplenectomy, we conducted intraoperative FVI-ICG. Because strong fluorescence was detected, we were able to safely preserve the remnant stomach. At 4 and 8 months after surgery, computed tomography showed good blood flow through the remnant stomach. FVI-ICG is useful for evaluating the blood supply to tissues, and hence, can be used to predict the blood supply of residual organs.

The use of near-infrared fluorescence imaging in endocrine surgical procedures

Near-infrared fluorescence imaging in endocrine surgery is a new, yet highly investigated area. It involves indocyanine green use as well as parathyroid autofluorescence. Several groups have described their technique and reported on the observed utility. However, there is no consensus on technical details. Furthermore, the correlation between intraoperative findings and postoperative outcomes is unclear. With this study, we aim to review the current literature on fluorescence imaging and share our insights on technical details.

Fluorescent Imaging With Indocyanine Green During Laparoscopic Cholecystectomy in Patients at Increased Risk of Bile Duct Injury

BACKGROUND

Although rare, injury to the common bile duct (CBD) during laparoscopic cholecystectomy (LC) can be reduced by better intraoperative visualization of the cystic duct (CD) and CBD. The aim of this study was to establish the efficacy of early visualization of the CD and the added value of CBD identification, using near-infrared (NIR) light and the fluorescent agent indocyanine green (ICG), in patients at increased risk of bile duct injury.

MATERIALS AND METHODS

Patients diagnosed with complicated cholecystitis and scheduled for LC were included. The CBD and CD were visualized with NIR light before and during dissection of the liver hilus and at critical view of safety (CVS).

RESULTS

Of the 20 patients originally included, 2 were later excluded due to conversion. In 6 of 18 patients, the CD was visualized early during dissection and prior to imaging with conventional white light. The CBD was additionally visualized with ICG-NIR in 7 of 18 patients. In 1 patient, conversion was prevented due to detection of the CD and CBD with ICG-NIR.

CONCLUSIONS

Early visualization of the CD or additional identification of the CBD using ICG-NIR in patients with complicated cholecystolithiasis can be helpful in preventing CBD injury. Future studies should attempt to establish the optimal dosage and time frame for ICG administration and bile duct visualization with respect to different gallbladder pathologies.

Benchmarking of fluorescence cameras through the use of a composite phantom

Fluorescence molecular imaging (FMI) has shown potential to detect and delineate cancer during surgery or diagnostic endoscopy. Recent progress on imaging systems has allowed sensitive detection of fluorescent agents even in video rate mode. However, lack of standardization in fluorescence imaging challenges the clinical application of FMI, since the use of different systems may lead to different results from a given study, even when using the same fluorescent agent. In this work, we investigate the use of a composite fluorescence phantom, employed as an FMI standard, to offer a comprehensive method for validation and standardization of the performance of different imaging systems. To exclude user interaction, all phantom features are automatically extracted from the acquired epi-illumination color and fluorescence images, using appropriately constructed templates. These features are then employed to characterize the performance and compare different cameras to each other. The proposed method could serve as a framework toward the calibration and benchmarking of FMI systems, to facilitate their clinical translation.

A collaborative review of the current concepts and challenges of anastomotic leaks in colorectal surgery

The reduction of the incidence, detection and treatment of anastomotic leakage (AL) continues to challenge the colorectal surgical community. AL is not consistently defined and reported in clinical studies, its occurrence is variably reported and its impact on longterm morbidity and health-care resources has received relatively little attention. Controversy continues regarding the best strategies to reduce the risk. Diagnostic tests lack sensitivity and specificity, resulting in delayed diagnosis and increased morbidity. Intra-operative fluorescence angiography has recently been introduced as a means of real-time assessment of anastomotic perfusion and preliminary evidence suggests that it may reduce the rate of AL. In addition, concepts are emerging about the role of the rectal mucosal microbiome in AL and the possible role of new prophylactic therapies. In January 2016 a meeting of expert colorectal surgeons and pathologists was held in London, UK, to identify the ongoing controversies surrounding AL in colorectal surgery. The outcome of the meeting is presented in the form of research challenges that need to be addressed.

Cystic duct variation detected by near-infrared fluorescent cholangiography during laparoscopic cholecystectomy

Near-infrared fluorescent cholangiography (NIRFC) is an emerging technique for easy intraoperative recognition of biliary anatomy. We present a case of cystic duct variation detected by NIRFC which had a potential risk for biliary injury if not detected. A 32-year-old female was admitted to the Seoul St. Mary's Hospital for surgery for an incidental gallbladder polyp. We performed laparoscopic cholecystectomy with NIRFC. In fluorescence mode, a long cystic duct and an accessory short hepatic duct joining to the cystic duct were found and the operation was completed safely. The patient recovered successfully. NIRFC is expected to be a promising procedure that will help minimize biliary injury during laparoscopic cholecystectomy.

Next generation ultrasound platforms for theranostics

Microbubbles are a well-established contrast agent which improves diagnostic ultrasound imaging. During the last decade research has focused on expanding their use to include molecular imaging, targeted therapy and imaging modalities other than ultrasound. However, bioadhesion of targeted microbubbles under physiological flow conditions is still difficult to achieve, the main challenge being connected to the poor stability of lipid microbubbles in the body's circulation system. In this article, we investigate the use of polymeric microbubbles based on a poly (vinyl alcohol) shell as an alternative to lipid microbubbles. In particular, we report on the development of microbubble shell modification, using mild reaction conditions, with the aim of designing a multifunctional platform to enable diagnosis and therapy. Superparamagnetic iron oxide nanoparticles and a near infrared fluorescent probe, indocyanine green, are coupled to the bubbles surface in order to support magnetic resonance and fluorescence imaging. Furthermore, anchoring cyclic arginyl-glycyl-aspartic acid (RGD) peptide, and cyclodextrin molecules, allows targeting and drug loading, respectively. Last but not least, shell topography is provided by atomic force microscopy. These applications and features, together with the high echogenicity of poly (vinyl alcohol) microbubbles, may offer a more stable alternative to lipid microbubbles for the development of a multimodal theranostic platform.

Clinical role of fluorescence imaging in colorectal surgery - a review

INTRODUCTION

Anastomotic leak (AL) after colorectal surgery is a devastating complication; decreased blood perfusion is an important risk factor. Surgeons rely on subjective measures to assess bowel perfusion. Fluorescence imaging (FI) with indocyanine green (ICG) provides a real-time objective assessment of intestinal perfusion. Areas covered: A PubMed search using the terms 'fluorescence imaging', 'indocyanine green', 'colon and rectal surgery' was undertaken. Sixteen articles between 2010 to present were identified. Main outcomes were leak rate reduction, change in surgical plan, and technical feasibility. Change in surgical strategy due to FI was recorded in 11 studies. Two case control studies showed overall reduction of 4% and 12% in AL rate and one showed no change in AL rate between groups. Expert commentary: According to the available literature, FI is technically feasible and alters surgical strategy in a non-negligible number of patients possibly effecting AL rates.

Quantification of fluorescence angiography in a porcine model

PURPOSE

There is no consensus on how to quantify indocyanine green (ICG) fluorescence angiography. The aim of the present study was to establish and gather validity evidence for a method of quantifying fluorescence angiography, to assess organ perfusion.

METHODS

Laparotomy was performed on seven pigs, with two regions of interest (ROIs) marked. ICG and neutron-activated microspheres were administered and the stomach was illuminated in the near-infrared range, parallel to continuous recording of fluorescence signal. Tissue samples from the ROIs were sent for quantification of microspheres to calculate the regional blood flow. A software system was developed to assess the fluorescent recordings quantitatively, and each quantitative parameter was compared with the regional blood flow. The parameter with the strongest correlation was then compared with results from an independently developed algorithm, to evaluate reproducibility.

RESULTS

A strong correlation was found between regional blood flow and the slope of the fluorescence curves (ROI I: Pearson r = 0.97, p < 0.001; ROI II: 0.96, p < 0.001) as the normalized slope (ROI I: Pearson r = 0.92, p = 0.004; ROI II: r = 0.96, p = 0.001). There was acceptable correlation of the slope of the curve between two independently developed algorithms (ROI I+II: Pearson r = 0.83, p < 0.001), and good resemblance was found with the Bland-Altman method, with no proportional bias.

CONCLUSIONS

Perfusion assessment with quantitative indocyanine green fluorescence angiography is not only feasible but easy to perform with commercially available equipment and readily accessible software.

Biliary tract visualization using near-infrared imaging with indocyanine green during laparoscopic cholecystectomy: results of a systematic review

Background

Near-infrared imaging with indocyanine green (ICG) has been extensively investigated during laparoscopic cholecystectomy (LC). However, methods vary between studies, especially regarding patient selection, dosage and timing. The aim of this systematic review was to evaluate the potential of the near-infrared imaging technique with ICG to identify biliary structures during LC.

Methods

A comprehensive systematic literature search was performed. Prospective trials examining the use of ICG during LC were included. Primary outcome was biliary tract visualization. Risk of bias was assessed using ROBINS-I. Secondly, a meta-analysis was performed comparing ICG to intraoperative cholangiography (IOC) for identification of biliary structures. GRADE was used to assess the quality of the evidence.

Results

Nineteen studies were included. Based upon the pooled data from 13 studies, cystic duct (Lusch et al. in J Endourol 28:261–266, 2014) visualization was 86.5% (95% CI 71.2–96.6%) prior to dissection of Calot’s triangle with a 2.5-mg dosage of ICG and 96.5% (95% CI 93.9–98.4%) after dissection. The results were not appreciably different when the dosage was based upon bodyweight. There is moderate quality evidence that the CD is more frequently visualized using ICG than IOC (RR 1.16; 95% CI 1.00–1.35); however, this difference was not statistically significant.

Conclusion

This systematic review provides equal results for biliary tract visualization with near-infrared imaging with ICG during LC compared to IOC. Near-infrared imaging with ICG has the potential to replace IOC for biliary mapping. However, methods of near-infrared imaging with ICG vary. Future research is necessary for optimization and standardization of the near-infrared ICG technique.

Electronic supplementary material

The online version of this article (doi:10.1007/s00464-016-5318-7) contains supplementary material, which is available to authorized users.

Indocyanine green-enhanced fluorescence for assessing parathyroid perfusion during thyroidectomy

Identification of the parathyroid glands during thyroid surgery may prevent their inadvertent surgical removal and thus provide a better postoperative quality of life. Nevertheless, the most common "technique" for intraoperative evaluation of perfusion of parathyroid gland tissues during thyroid surgery is visual inspection of the physical condition of tissues, e.g., their color and bleeding edges. Another technique is measurement of intact parathyroid hormone. Recently, indocyanine green-enhanced fluorescence has been used in various surgical techniques, particularly laparoscopic surgery, to improve visualization and to provide detailed anatomical information. Fluorescent optical guidance helps surgeons to avoid inadvertent tissue injury while enhancing procedural efficiency. This technique has potential use for evaluating perfusion of the parathyroid gland in real-time intraoperative angiography.

Applications of indocyanine green in robotic urology

Indocyanine green is a fluorescent molecule with wide ranging applications in minimally invasive urological surgery. This article explores the utility of ICG assisted intraoperative fluorescence in robotic urology.

Lasing in blood

Indocyanine green (ICG) is the only near-infrared dye approved by the U.S. Food and Drug Administration for clinical use. When injected in blood, ICG binds primarily to plasma proteins and lipoproteins, resulting in enhanced fluorescence. Recently, the optofluidic laser has emerged as a novel tool in bio-analysis. Laser emission has advantages over fluorescence in signal amplification, narrow linewidth, and strong intensity, leading to orders of magnitude increase in detection sensitivity and imaging contrast. Here we successfully demonstrate, to the best of our knowledge, the first ICG lasing in human serum and whole blood with the clinical ICG concentrations and the pump intensity far below the clinically permissible level. Furthermore, we systematically study ICG laser emission within each major serological component (albumins, globulins, and lipoproteins) and reveal the critical elements and conditions responsible for lasing. Our work marks a critical step toward eventual clinical and biomedical applications of optofluidic lasers using FDA approved fluorophores, which may complement or even supersede conventional fluorescence-based sensing and imaging.

Optical imaging probes in oncology

Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management.Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation.The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed.

Indocyanine Green Guided Pelvic Lymph Node Dissection: An Efficient Technique to Classify the Lymph Node Status of Patients with Prostate Cancer Who Underwent Radical Prostatectomy

PURPOSE

We evaluated the effectiveness of indocyanine green guided pelvic lymph node dissection for the optimal staging of prostate cancer and analyzed whether the technique could replace extended pelvic lymph node dissection.

MATERIALS AND METHODS

A solution of 25 mg indocyanine green in 5 ml sterile water was transperineally injected. Pelvic lymph node dissection was started with the indocyanine green stained nodes followed by extended pelvic lymph node dissection. Primary outcome measures were sensitivity, specificity, predictive value and likelihood ratio of a negative test of indocyanine green guided pelvic lymph node dissection.

RESULTS

A total of 84 patients with a median age of 63.55 years and a median prostate specific antigen of 8.48 ng/ml were included in the study. Of these patients 60.7% had intermediate risk disease and 25% had high or very high risk disease. A median of 7 indocyanine green stained nodes per patient was detected (range 2 to 18) with a median of 22 nodes excised during extended pelvic lymph node dissection. Lymph node metastasis was identified in 25 patients, 23 of whom had disease properly classified by indocyanine green guided pelvic lymph node dissection. The most frequent location of indocyanine green stained nodes was the proximal internal iliac artery followed by the fossa of Marcille. The negative predictive value was 96.7% and the likelihood ratio of a negative test was 8%. Overall 1,856 nodes were removed and 603 were stained indocyanine green. Pathological examination revealed 82 metastatic nodes, of which 60% were indocyanine green stained. The negative predictive value was 97.4% but the likelihood ratio of a negative test was 58.5%.

CONCLUSIONS

Indocyanine green guided pelvic lymph node dissection correctly staged 97% of cases. However, according to our data it cannot replace extended pelvic lymph node dissection. Nevertheless, its high negative predictive value could allow us to avoid extended pelvic lymph node dissection if we had an accurate intraoperative lymph fluorescent analysis.

Indocyanine green delivery systems for tumour detection and treatments

Indocyanine green (ICG) is a cyanine compound that displays fluorescent properties in the near infrared region. This dye is employed for numerous indications but nowadays its major application field regards tumour diagnosis and treatments. Optical imaging by near infrared fluorescence provides news opportunities for oncologic surgery. The imaging of ICG can be useful for intraoperative identification of several solid tumours and metastases, and sentinel lymph node detection. In addition, ICG can be used as an agent for the destruction of malignant tissue, by virtue of the production of reactive oxygen species and/or induction of a hyperthermia effect under irradiation. Nevertheless, ICG shows several drawbacks, which limit its clinical application. Several formulative strategies have been studied to overcome these problems. The rationale of the development of ICG containing drug delivery systems is to enhance the in vivo stability and biodistribution profile of this dye, allowing tumour accumulation and resulting in better efficacy. In this review, ICG containing nano-sized carriers are classified based on their chemical composition and structure. In addition to nanosystems, different formulations including hydrogel, microsystems and others loaded with ICG will be illustrated. In particular, this report describes the preparation, in vitro characterization and in vivo application of ICG platforms for cancer imaging and treatment. The promising results of all systems confirm their clinical utility but further studies are required prior to evaluating the formulations in human trials.

Colectomy in patients with previous colectomy or occlusive vascular diseases: Pitfalls and precautions

Two principal branches from the aorta provide the colonic blood supply: the superior and inferior mesenteric arteries. There are numerous anatomical variations, which the surgeon must fully understand before embarking on any colonic surgery. A good knowledge of these variations is particularly important when the patient has already undergone colectomy or presents with occlusive vascular disease. The aim of this review is to summarize the standard anatomy and the main variations of the colonic blood supply as they apply to colorectal surgery in this setting.

Indocyanine green fluorescence angiography for intraoperative assessment of gastrointestinal anastomotic perfusion: a systematic review of clinical trials

PURPOSE

Anastomotic leakage following gastrointestinal surgery remains a frequent and serious complication associated with a high morbidity and mortality. Indocyanine green fluorescence angiography (ICG-FA) is a newly developed technique to measure perfusion intraoperatively. The aim of this paper was to systematically review the literature concerning ICG-FA to assess perfusion during the construction of a primary gastrointestinal anastomosis in order to predict anastomotic leakage.

METHODS

The following four databases PubMed, Scopus, Embase, and Cochrane were independently searched by two authors. Studies were included in the review if they assessed anastomotic perfusion intraoperatively with ICG-FA in order to predict anastomotic leakage in humans.

RESULTS

Of 790 screened papers 14 studies were included in this review. Ten studies (n = 916) involved patients with colorectal anastomoses and four studies (n = 214) patients with esophageal anastomoses. All the included studies were cohort studies. Intraoperative ICG-FA assessment of colorectal anastomoses was associated with a reduced risk of anastomotic leakage (n = 23/693; 3.3 % (95 % CI 1.97-4.63 %) compared with no ICG-FA assessment (n = 19/223; 8.5 %; 95 % CI 4.8-12.2 %). The anastomotic leakage rate in patients with esophageal anastomoses and intraoperative ICG-FA assessment was 14 % (n = 30/214). None of the studies involving esophageal anastomoses had a control group without ICG-FA assessment.

CONCLUSION

No randomized controlled trials have been published. ICG-FA seems like a promising method to assess perfusion at the site intended for anastomosis. However, we do not have the sufficient evidence to determine that the method can reduce the leak rate.

A specific photoimmunotheranostics agent to detect and eliminate skin cancer cells expressing EGFR

PURPOSE

The term "theranostics" represents a new paradigm in medicine especially for cancer treatment. This term was coined by Funkhouser in 2002 and defines a reagent that combines therapeutic and diagnostic properties. It is widely believed that theranostics agents will have considerable impact on healthcare before, during, and after disease by improving cancer prognosis and management simultaneously. Current theranostics approaches still rely on passive tumor targeting strategies, which have scattergun effects and tend to damage both neoplastic and non-neoplastic cells.

METHODS

Here we describe a simple, controlled, and efficient method to generate homogeneous photoimmunotheranostics reagents. This method combines molecular optical imaging, photodynamic therapy, and immunotherapy using SNAP-tag technology. SNAP-tag is a derivative of the O(6)-alkylguanine-DNA alkyltransferase (AGT) which has the ability to efficiently conjugate to O(6)-benzylguanine (BG) molecules under physiological conditions depending on its folding pattern.

RESULTS

The theranostics agent was able to specifically recognize various epidermal growth factor receptor (EGFR)-expressing skin cancer cell lines using flow cytometry analysis and confocal microscopy and eliminate them at EC50's of 32-55 nM.

CONCLUSIONS

These experiments provide a framework for using SNAP-tag technology to generate homogeneous photoimmunotheranostics reagents with unified pharmacokinetic and therapeutic profiles. Furthermore, the reagent generated in this work could be used to simultaneously monitor and suppress the growth of skin squamous carcinoma and melanoma cells expressing EGFR.

Indocyanine green-enhanced fluorescence in laparoscopic sleeve gastrectomy

The aim of this study is to present our preliminary experience with indocyanine green fluorescence (IGF) imaging in laparoscopic sleeve gastrectomy. After dissection of the greater curve sleeve, gastrectomy is performed using a linear articulated stapler. Once the stomach is resected, an indocyanine green solution is prepared and injected in a periferic vein. A laparoscopic system with a high-definition camera system connected to a laparoscope equipped with a specific filter for optimal detection of the near-infrared fluorescence was used at all times as previously reported in a paper of Boni et al. A methylene blue test is routinely performed after near-infrared fluorescence, and a routine gastrografin upper gastrointestinal study is performed on postoperative day 2. We retrospectively identified 15 patients undergoing laparoscopic sleeve gastrectomy between April and October 2014. IGF imaging was used for all patients. A regular and homogeneous perfusion was observed along the entire gastric sleeve including the esophago-gastric junction. On the contrary, the excised specimen appeared devascularized at IGF imaging as expected. Intraoperative methylene blue test was negative in all cases. The contrast swallow did not document any leak. Neither clinical leak nor other complications occurred postoperatively (minimum follow-up of 2 months). IGF is a recent development in minimally invasive surgery. In this preliminary experience, IGF results resemble to intraoperative methylene blue test and postoperative contrast swallow ones. IGF allows a real-time assessment and gives a direct image of tissue perfusion and vascularization. Moreover, IGF may be helpful to explain the exact pathogenesis of gastric leak.

Utility of Indocyanine Green Fluorescence Imaging for Intraoperative Localization in Reoperative Parathyroid Surgery

Background. Due to the variations in anatomic location, the identification of parathyroid glands may be challenging. Although there have been advances in preoperative imaging modalities, there is still a need for an accurate intraoperative guidance. Indocyanine green (ICG) is a new agent that has been used for intraoperative fluorescence imaging in a number of general surgical procedures. Its utility for parathyroid localization in humans has not been reported in the literature. Results. We report 3 patients who underwent reoperative neck surgery for primary hyperparathyroidism. Using a video-assisted technique with intraoperative ICG fluorescence imaging, the parathyroid glands were recognized and removed successfully in all cases. Surrounding soft tissue structures remained nonfluorescent, and could be distinguished from the parathyroid glands. Conclusions. This report suggests a potential utility of ICG imaging in intraoperative localization of parathyroid glands in reoperative neck surgery. Future work is necessary to assess its benefit for first-time parathyroid surgery.

Utility of indocyanine-green fluorescent imaging during robot-assisted sphincter-saving surgery on rectal cancer patients

BACKGROUND

There have been few studies describing the use of indocyanine green (ICG) fluorescent imaging during robot-assisted (RA) sphincter-saving operations (SSOs) and assessing its potential role in reducing anastomotic leak (AL).

METHODS

A consecutive cohort of 436 rectal cancer patients who underwent curative RA SSOs were prospectively enrolled during 2010-2014, including 123 patients with ICG imaging (ICG⁺ group) and 313 patients without ICG imaging (ICG^- group).

RESULTS

ICG imaging appeared to be helpful in identifying competent perfusion of the bowel adjacent to the anastomosis in 13 patients (10.6%) who might be susceptible to bowel ischaemia, including restrictive mesocolon. AL was remarkably greater in the ICG^- group compared with the ICG⁺ group (5.4% vs 0.8%; p = 0.031).

CONCLUSIONS

ICG imaging during RA SSO provides accurate real-time knowledge of the perfusion status at or near the anastomosis, specifically reducing AL in patients who may incur bowel ischaemia. Copyright © 2015 John Wiley & Sons, Ltd.

Indocyanine green-enhanced fluorescence to assess bowel perfusion during laparoscopic colorectal resection

Aims

Anastomotic leakage after colorectal surgery is a severe complication. One possible cause of anastomotic leakage is insufficient vascular supply. The aim of this study was to evaluate the feasibility and the usefulness of intraoperative assessment of vascular anastomotic perfusion in colorectal surgery using indocyanine green (ICG)-enhanced fluorescence.

Methods

Between May 2013 and October 2014, all anastomosis and resection margins in colorectal surgery were investigated using fluorescence angiography (KARL STORZ GmbH & Co. KG, Tuttlingen, Germany) intraoperatively to assess colonic perfusion prior to and after completion of the anastomosis, both in right and left colectomies.

Results

A total of 107 patients undergoing colorectal laparoscopic resections were enrolled: 40 right colectomies, 10 splenic flexure segmental resections, 35 left colectomies, and 22 anterior resections. In 90 % of cases, the indication for surgery was cancer and high ligation of vessels was performed. Based on the fluorescence intensity, the surgical team judged the distal part of the proximal bowel to be anastomosed insufficiently perfused in 4/107 patients (two anterior, one sigmoid and one segmental splenic flexure resections for cancer), and consequently, further proximal “re-resection” up to a “fluorescent” portion was performed. None of these patients had a clinical leak. The overall morbidity rate was 30 %; one patient undergoing right colectomy had an anastomotic leakage, apparently unrelated to ischemia; there were no clinical evident anastomotic leakages in colorectal resections including all low anterior resections.

Conclusions

ICG-enhanced fluorescent angiography provides useful intraoperative information about the vascular perfusion during colorectal surgery and may lead to change the site of resection and/or anastomosis, possibly affecting the anastomotic leak rate. Larger further randomized prospective trials are needed to validate this new technique.

Review of fluorescence guided surgery visualization and overlay techniques

In fluorescence guided surgery, data visualization represents a critical step between signal capture and display needed for clinical decisions informed by that signal. The diversity of methods for displaying surgical images are reviewed, and a particular focus is placed on electronically detected and visualized signals, as required for near-infrared or low concentration tracers. Factors driving the choices such as human perception, the need for rapid decision making in a surgical environment, and biases induced by display choices are outlined. Five practical suggestions are outlined for optimal display orientation, color map, transparency/alpha function, dynamic range compression, and color perception check.

Intraoperative tumor localization and tissue distinction during robotic adrenalectomy using indocyanine green fluorescence imaging: a feasibility study

BACKGROUND

To investigate the feasibility of a method for intraoperative tumor localization and tissue distinction during robotic adrenalectomy (RA) via indocyanine green (ICG) imaging under near-infrared light.

METHODS

Ten patients underwent RA. After exposure of the retroperitoneal space, but before adrenal dissection was started, ICG was given intravenously (IV). Fluorescence Firefly™ imaging was performed at 1-, 5-, 10-, and 20-min time points. The precision with which the borders of the adrenal tissue were distinguished with ICG imaging was compared to that with the conventional robotic view. The number and the total volume of injections for each patient were recorded.

RESULTS

There were six male and four female patients. Diagnosis was primary hyperaldosteronism in four patients and myelolipoma, adrenocortical neoplasm, adrenocortical hyperplasia, Cushing's syndrome, pheochromocytoma, and metastasis in one patient each. Procedures were done through a robotic lateral transabdominal approach in nine and through a robotic posterior retroperitoneal approach in one patient. Dose per injection ranged between 2.5 and 6.3 mg and total dose per patient 7.5-18.8 mg. The adrenal gland took up the dye in 1 min, with contrast between adrenal mass and surrounding retroperitoneal fat becoming most distinguished at 5 min. Fluorescence of adrenal tissue lasted up to 20 min after injection. Overall, ICG imaging was felt to help with the conduct of operation in 8 out of 10 procedures. There were no conversions to open or morbidity. There were no immediate or delayed adverse effects attributable to IV ICG administration.

CONCLUSION

In this pilot study, we demonstrated the feasibility and safety of ICG imaging in a small group of patients undergoing RA. We described a method that enabled an effective fluorescence imaging to localize the adrenal glands and guide dissection. Future research is necessary to study how this imaging affects perioperative outcomes.

Recent advances in near-infrared fluorescence-guided imaging surgery using indocyanine green

Near-infrared (NIR) fluorescence imaging has better tissue penetration, allowing for the effective rejection of excitation light and detection deep inside organs. Indocyanine green (ICG) generates NIR fluorescence after illumination by an NIR ray, enabling real-time intraoperative visualization of superficial lymphatic channels and vessels transcutaneously. The HyperEye Medical System (HEMS) can simultaneously detect NIR rays under room light to provide color imaging, which enables visualization under bright light. Thus, NIR fluorescence imaging using ICG can provide for excellent diagnostic accuracy in detecting sentinel lymph nodes in cancer and microvascular circulation in various ischemic diseases, to assist us with intraoperative decision making. Including HEMS in this system could further improve the sentinel lymph node mapping and intraoperative identification of blood supply in reconstructive organs and ischemic diseases, making it more attractive than conventional imaging. Moreover, the development of new laparoscopic imaging systems equipped with NIR will allow fluorescence-guided surgery in a minimally invasive setting. Future directions, including the conjugation of NIR fluorophores to target specific cancer markers might be realistic technology with diagnostic and therapeutic benefits.

In vivo inflammation imaging using a CB2R-targeted near infrared fluorescent probe

Chronic inflammation is considered as a critical cause of a host of disorders, such as cancer, rheumatoid arthritis, atherosclerosis, and neurodegenerative diseases, although the exact mechanism is yet to be explored. Imaging tools that can specifically target inflammation are therefore important to help reveal the role of inflammation in disease progression, and allows for developing new therapeutic strategies to ultimately improve patient care. The purpose of this study was to develop a new in vivo inflammation imaging approach by targeting the cannabinoid receptor type 2 (CB2R), an emerging inflammation biomarker, using a unique near infrared (NIR) fluorescent probe. Herein, we report the first in vivo CB2R-targeted NIR inflammation imaging study using a synthetic fluorescent probe developed in our laboratory, NIR760-mbc94. In vitro binding assay and fluorescence microscopy study indicate NIR760-mbc94 specifically binds towards CB2R in mouse RAW264.7 macrophage cells. Furthermore, in vivo imaging was performed using a Complete Freund's Adjuvant (CFA)-induced inflammation mouse model. NIR760-mbc94 successfully identified inflamed tissues and the probe uptake was blocked by a CB2R ligand, SR144528. Additionally, immunofluorescence staining in cryosectioned tissues validated the NIR760-mbc94 uptake in inflamed tissues. In conclusion, this study reports the first in vivo CB2R-targeted inflammation imaging using an NIR fluorescent probe. Specific targeting of NIR760-mbc94 has been demonstrated in macrophage cells, as well as a CFA-induced inflammation mouse model. The combined evidence indicates that NIR760-mbc94 is a promising inflammation imaging probe. Moreover, in vivo CB2R-targeted fluorescence imaging may have potential in the study of inflammation-related diseases.